1. Technical Field
The present invention relates to disk drives in general, and in particular to hard disks that can be attached and removed at will to/from a hard disk controller. Still more particularly, the present invention relates to a method and apparatus for controlling data read/write between a hard disk and a hard disk controller.
2. Description of the Related Art
Hard disks are widely used as external storage devices for computers. A hard disk is equipped with magnetic heads for reading and writing data from/to a magnetic disk. The magnetic heads are connected to an actuator mechanism whose position is controlled by means of a Voice Coil Motor (VCM). When a magnetic head reads or writes data, the actuator mechanism is operated to move and position the magnetic head on an appropriate track. The movement of the magnetic heads is controlled based on servo information stored on the magnetic disk so that magnetic heads will be placed in position.
FIG. 5 is a block diagram of a conventional hard disk drive (HDD) 31. The HDD 31 is a data storage device in which magnetic heads 34 seek on a magnetic disk 32 that is rotationally driven by a spindle motor 33, and write data to the magnetic disk 32 or read data from the magnetic disk 32.
The magnetic disk 32 is rotationally driven around the spindle axis of the spindle motor 33 controlled by a spindle driver 39 when the HDD 31 is operating, but stops rotating when the HDD 31 is not operating. Positional information storage areas are formed along radial lines on surfaces of the magnetic disk 32 and data storage areas are formed in the remaining areas of the magnetic disk 32. The magnetic heads 34 read this servo information to locate themselves.
Two magnetic heads 34 for the top and bottom surfaces of the magnetic disk 32 are held at a tip of an actuator 35. The magnetic heads 34 read and write data from/to the magnetic disk 32. They also read the servo information from the magnetic disk 32. The magnetic heads 34 move radially over the magnetic disk 32 together with the actuator 35. A ramp (not shown) is provided outside the magnetic disk 32 to park the magnetic heads 34 when they are not driven.
A read/write channel 41 processes data read/write operation. Specifically, read/write channel 41 converts write data transferred from a host computer 50 via an hard disk controller (HDC) 43 into a write signal and supplies it to the magnetic heads 34 via a write driver in a preamplifier 46. Based on the write current, the magnetic heads 34 write data to the magnetic disk 32. On the other hand, a read signal read from the magnetic disk 32 is amplified by the preamplifier 46, converted into digital data by the read/write channel 41, and output to the host computer 50 via the HDC 43.
A servo controller 44 extracts servo information from the read data outputted from the read/write channel 41. The servo controller 44 transfers the extracted servo information to an micro processing unit (MPU) 42. The actuator 35 is driven by a voice coil motor (VCM) 36. The VCM 36 comprises an actuator having a coil and a stator that is made of permanent magnets. As a predetermined current is supplied to the coil from a VCM driver 38, the actuator is driven in such a way that the magnetic heads 34 will be moved to or stopped at a predetermined position on the magnetic disk 32.
The HDC 43 functions as an interface for the HDD 31. The functions of the HDC 43 include receiving the write data transferred from the host computer 50 and transferring the received write data to a buffer 45. The write data stored temporarily in the buffer 45 is read by the HDC 43 and transferred to the read/write channel 41 based on instruction from the MPU 42. Also, the HDC 43 transfers read data received from the read/write channel 41 to the host computer 50.
The MPU 42 and HDC 43 control the function of the HDD 31 in conjunction with each other. The MPU 42 interprets and executes programs stored in a memory (not shown). The MPU 42 determines the position of the magnetic heads 34 based on the servo information transferred from the servo controller 44 and outputs an actuator current for positioning for the magnetic heads 34 to a digital/analog converter (DAC) 37 based on the distance between the determined position of the magnetic heads 34 and a target position.
The DAC 37 converts the actuator current for positioning outputted from the MPU 42 into an analog voltage signal and outputs it to the VCM driver 38. The VCM driver 38 converts the analog voltage signal received from the DAC 37 into a drive current and supplies it to the VCM 36. The above components are contained in a housing and the entire housing is connected to a computer device.
Normally, an HDD connected to a computer device is removed and attached only under exceptional circumstances such as HDD malfunctioning. As far as computer devices are concerned, there has not been much need to attach and detach a large-capacity HDD at will. Storage media that can be attached and removed at will to/from computer devices are available. However, data storage devices as large as an HDD capable of being freely attachable/removable to/from computer devices are not in common use. An HDD that the user can attach and remove freely will be useful, for example, for audio visual (AV) devices. Of course, if a large-capacity HDD can be attached and removed at will to/from computer devices other than AV devices, the user will need to have only a single HDD for two or more computer devices.
When considering a freely attachable/removable HDD, it is necessary to allow for compatibility among generations and reduce costs by minimizing the number of parts so that users can use it easily. Consequently, it would be desirable to provide an improved method and apparatus for controlling data read/write between a hard disk and a hard disk controller.